The invention relates to the treatment of gas streams. In another aspect, the invention relates to treating an acid gas stream with an amine solution. In yet another aspect, the invention relates to regenerating alkanolamine solution which has been used to treat acid gases.
The use of amines for the removal of hydrogen sulfide and carbon dioxide from gas streams is well known. Triethanolamine (TEA) was the first of the ethanol amines to become commercially available. It was used in the early gas treating plant. This amine has generally been replaced in gas treating plants by diethanolamine (DEA), monoethanol amine (MEA), and methyldiethanolamine (MDEA). The advantage to the use of DEA, MEA and MDEA lies in the lower molecular weights and their ability to more completely absorb hydrogen sulfide from the gas. Changeout of the working fluid of the gas treater from TEA to MEA, DEA or MDEA was also easily accomplished. Of these three amines, monoethanol amine is generally preferred because of its ability to produce sweet gas streams with extremely low hydrogen sulfide levels under the same operating conditions.
A problem encountered frequently in gas treating plants relates to replenishing water which is lost from the amine solution. It has generally been thought necessary to use condensate or water which had been distilled or in other ways treated to a very low solids content in order to maintain the gas treating unit in good operating condition. For remote treating units, the requirement of using specially treated make-up water was very burdensome.
It would thus be desirable to provide an amine treating unit in which specially treated make-up water is not required to maintain good operation. It would also be desirable to provide a process for treating streams containing acid gases which does not require specially treated make-up water.